This invention relates to incandescent lamps and more particularly to general purpose lamps having a particular emission spectra. Still more particularly, it relates to lamps useful for household lighting and has still greater applicability where enhanced skin tones are desired.
Common household incandescent lamps emit light that is high in the yellow/green portion of the spectrum. While suitable for most illumination it has been objected to as being deficient when it come to illuminating normal skin tones. A recent development in the art has provided a general purpose household lamp with strong emission in the blue/white portion of the spectrum which has been deemed to provide a more aesthetically pleasing appearance, especially when the important skin tone appearance is considered. However, this particular blue/white spectrum has been achieved by developing a new glass for the lamp envelope, which glass uses an additive of neodymium in the form of Nd2O3, a material which adds approximately 15-20 cents to the cost of the lamp envelope. It would be an advance in the art to provide a lamp that has a similar color output at a more conventional cost.
It is, therefore, an object of the invention to obviate the disadvantages of the prior art.
It is another object of the invention to enhance general purpose household lamps.
It is yet another object of the invention to provide a general purpose household lamp lamp that is environmentally safe, allowing the spent lamp to be landfilled.
These objects are accomplished, in one aspect of the invention, by the provision of an electric lamp which emits a blue color when energized and which comprises a light transmissive envelope formed from a typical soda/lime glass and enclosing an electric light source within. The envelope has an internal surface on which is a coating comprising precipitated silica, aluminum silicate pigment, manganese ammonium pyro phosphate and cobalt aluminate spinel.
The soft blue color provides a higher color temperature and enhances the lighting appearance, particularly of skin tones. The internal powder coating uses an environmentally safe formula that enables the spent lamp to be landfilled.